Wireless intelligent switch engine

ABSTRACT

A wireless intelligent switch engine (WISE) is described. The wireless intelligent switch engine provides for automatic switching between different physical wireless interfaces in mobile devices while roaming to maintain a wireless network connection. WISE functions as a bridge between a mobile device and multiple wireless network interfaces to provide automatic and seamless switching among networks while roaming. The mobile device sees WISE as a LAN interface and communicates with WISE using the TCP/IP protocol stack, thus providing a PPP-less configuration that uses the TCP/IP protocol stack regardless of the wireless interface.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.10/387,362 filed on Mar. 11, 2003, now U.S. Pat. No. ______,incorporated herein by reference in its entirety, which claims priorityto U.S. application Ser. No. 60/429,480 filed on Nov. 26, 2002,incorporated herein by reference in its entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC

Not Applicable

NOTICE OF MATERIAL SUBJECT TO COPYRIGHT PROTECTION

A portion of the material in this patent document is subject tocopyright protection under the copyright laws of the United States andof other countries. The owner of the copyright rights has no objectionto the facsimile reproduction by anyone of the patent document or thepatent disclosure, as it appears in the United States Patent andTrademark Office publicly available file or records, but otherwisereserves all copyright rights whatsoever. The copyright owner does nothereby waive any of its rights to have this patent document maintainedin secrecy, including without limitation its rights pursuant to 37C.F.R. §1.14.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention pertains generally to wireless networking, and moreparticularly to an apparatus and method that provides for automaticswitching between different network interfaces in a mobile device sothat the mobile device can seamlessly roam among different types ofwireless networks.

2. Description of Related Art

In recent years, wireless network interfaces have become extremelyimportant to the functionality of mobile devices. Examples of mobiledevices that use wireless networking are laptop computers and personaldigital assistants (PDAs). Wireless connectivity of a mobile device tothe Internet or to an intranet can increase mobility, convenience andproductivity, but there are certain limitations associated with thatconnectivity. For example, the widely used IEEE 802.11 (WLAN) wirelessnetworking technology provides high bandwidth but is limited ingeographical coverage. On the other hand, while cellular technologiessuch as CDMA/WDCMA/GSM/GPRS (WAN) provide much wider (and even global)geographical coverage, they do so at a much lower bandwidth than 802.11networking.

Due to the use of different standards and communications protocols forwireless networking, in order to achieve true global coverage it iscurrently necessary to utilize a combination of several plug-in orintegrated connectivity interfaces and to manually switch betweeninterfaces while roaming through different geographical areas orcommunication sites. For example, a laptop computer or PDA may have anintegrated 802.11b interface and one or more PCMCIA or CF-card slots forswappable add-on cards. This allows the user to, for example, selectamong IEEE 802.11a, IEEE 802.11b, CDMA/WCDMA or GSM/GPRS wirelessinterface cards. Again, however, the user experiences a degree ofinconvenience since it is necessary to manually enable, disable orotherwise switch between the interfaces. For example, the user may haveto manually switch from an 802.11 module to a CDMA/WCDMA or GSM/GPRSmodule if the user moves from 802.11 hot spots to cellular networks.With many operating systems, this also requires the user to close thenetwork connection session and restart it again using the new wirelessinterface.

Those skilled in the art will appreciate that network communicationstypically rely on the Open Systems Interconnection (OSI) Reference Modelin which there are seven communications layers. Currently, products areavailable that use OSI Layer 5 to provide proxy-based session levelmobility and OSI Layer 3 with Mobile IP to provide network levelmobility. However, those products are based on a client/serverarchitecture and roaming connection changes require interactions of bothclient and server components.

Accordingly, there is a need for seamless roaming capability to bebuilt-in to mobile devices so that different wireless interfaces willautomatically be selected while roaming without the need for manualselection and/or restarting the wireless networking session. The presentinvention satisfies that need as will herein be described.

BRIEF SUMMARY OF THE INVENTION

The present invention provides for the automatic switching betweendifferent physical wireless interfaces in mobile devices while roamingto maintain a wireless network connection. In general terms, theinvention comprises a wireless intelligent switch engine (WISE) thatfunctions as a bridge to provide network connection switching betweendifferent interfaces.

According to an aspect of the invention, network connection switching isaccomplished through the use of Open Systems Interconnection (OSI) Layer2 Media Access Control (MAC) bridging technology. Those skilled in theart will appreciate that OSI specifies seven layers ranging from thephysical layer to the application layer. Layer 2, the data link layer,defines rules for sending/receiving data across the physical connectionbetween two systems.

In one embodiment, the present invention comprises a Layer 2 bridge thatprovides network switching between WLAN (802.11) or WAN(GSM/GPRS/CDMA/WCDMA) using 802.1p/802.1D/802.11 standards to select thedesired wireless interface. In one embodiment, the bridge resides withinthe mobile device. In another embodiment, the bridge is external to themobile device.

As can be seen, therefore, an object of the invention is to allow amobile device to connect to any wireless network seamlessly. Furtherobjects and aspects of the invention will be brought out in thefollowing portions of the specification, wherein the detaileddescription is for the purpose of fully disclosing preferred embodimentsof the invention without placing limitations thereon.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

The invention will be more fully understood by reference to thefollowing drawings which are for illustrative purposes only:

FIG. 1 is a schematic diagram of a wireless network connected to which amobile device is connected using a wireless intelligent switch engineaccording to the present invention.

FIG. 2 is a diagram showing the relationship of the protocol stacks in amobile device and a wireless intelligent switch engine according to thepresent invention.

FIG. 3 is a diagram showing an embodiment of the protocol stacks used ina wireless intelligent switch engine according to the present invention.

FIG. 4 is a diagram showing the Open Systems Interconnection (OSI)Reference Model with Layer 2 Media Access Control (MAC) used in thepresent invention.

FIG. 5 is a block diagram showing the internal architecture of thewireless intelligent switch engine of the present invention.

FIG. 6 is a block diagram showing the IEEE 802.1D protocol stackemployed in the present invention.

FIG. 7 is a block diagram showing the IEEE 802.1D internal organizationof the MAC sublayer employed in the present invention.

FIG. 8 is a block diagram showing the internal organization of the relayblock of FIG. 7.

FIG. 9 is a diagram showing the OSI Layer 2 packet header with IEEE802.1p tag control employed in the present invention.

FIG. 10 is a block diagram of a dual mode 802.11a/b configurationsupported by the wireless intelligent switch engine of the presentinvention.

FIG. 11 is a block diagram of a WLAN and WAN configuration supported bythe wireless intelligent switch engine of the present invention.

FIG. 12 is a block diagram of a dual WLAN and WAN configurationsupported by the wireless intelligent switch engine of the presentinvention.

FIG. 13 is a block diagram of a WLAN and dual WLAN configurationsupported by the wireless intelligent switch engine of the presentinvention.

FIG. 14 is a schematic diagram illustrating the wireless intelligentswitch engine of the present invention functioning as a gateway routerbetween a mobile device and wireless network according to the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

Referring more specifically to the drawings, for illustrative purposesthe present invention is embodied in the apparatus generally shown inFIG. 1 through FIG. 14. It will be appreciated that the apparatus mayvary as to configuration and as to details of the components, and thatthe method may vary as to the specific steps and sequence, withoutdeparting from the basic concepts as disclosed herein.

Referring first to FIG. 1, an example of a wireless network 10 is showncomprising a WAN 12 established by cellular carriers and a WLAN 14established by a high speed infrastructure, both of which are connectedeither wirelessly or by wired connections to the Internet 16. A mobiledevice 18, such as a laptop personal computer (PC) or personal digitalassistant (PDA), is also shown with capability of communicating withboth types of wireless networks. For seamless roaming between thosenetworks, mobile device 18 includes a wireless intelligent switch engine(WISE) according to the present invention as will now be described.

Preferably, the WISE is completely internal to the mobile device, but itwill be appreciated that the WISE can be implemented externally as well.WISE communicates with the mobile device and the wireless interfacedevices, functioning as a bridge between the mobile device and thewireless interface devices such that, as the mobile device roams amongthe wireless networks, WISE automatically selects the wireless interfaceassociated with the wireless network for seamless roaming. This isaccomplished, in part, by interfacing with the mobile device's TCP/IPprotocol stack.

Referring to FIG. 2 and FIG. 3, an example of the relationship betweenthe protocol stack of the mobile device and that of the WISE can beseen. As shown, the WISE 20 appears to mobile device 18 as a networkinterface card (NIC) 22, thus providing a PPP-less interface (PPP refersto Point-to-Point Protocol) is known in the with the mobile device'sTCP/IP protocol stack 24, and bridging mobile device 18 to the requiredwireless interface device such as WLAN interface device 26 and WANinterface device 28 shown. By functioning as a bridge between the mobiledevice and its associated wireless network interface devices, WISE 20allows for seamless roaming among different wireless networks.

The invention automatically switches between the wireless networkinterface devices using bridging technology that is based on the OpenSystems Interconnection (OSI) Reference Model. As shown in FIG. 4, OSIspecifies a physical layer 30 (Layer 1), a data link layer 32 (Layer 2),a network layer 34 (Layer 3), a transport layer 36 (Layer 4), a sessionlayer 38 (Layer 5), a presentation layer 40 (Layer 6) and an applicationlayer 42 (Layer 7). The bridging technology employed by the WISE of thepresent invention is based on OSI Layer 2 Media Access Control (MAC) andthe IEEE 802.1D bridging standard.

Referring now to FIG. 5, an embodiment of the WISE internal architecturecan be seen. In the embodiment shown, WISE 20 comprises a QoS PriorityQueuing module 50 (802.1p), a VLAN Bandwidth Tagging module 52 (802.1Q),a Bridge Switching module 54 (802.1D), a Switching/Packet ManagementTable 56, and a buffering module 58 to provide dynamic filtering andswitching between a plurality of wireless interfaces. Referring moreparticularly to FIG. 6, the IEEE 802.1D MAC Bridge specifies anarchitecture and protocol for the interconnection of networks below theMAC service boundary. The protocol stack 60 comprises 802.2 Logical LinkControl (LLC) 62 and 802.1D bridging 64 for communication with, forexample, 802.3 (Ethernet) MAC 66 and 802.11 (WLAN) MAC 68 at the OSIdata link layer 32 (Layer 2).

FIG. 7 and FIG. 8 illustrate an example of the internal organization ofthe

MAC sublayer based on 802.1D. In FIG. 7, a first network 70 with LLC 72and MAC 74 is shown interconnected to a second network 76 with LLC 78and MAC 80 by means of an 802.1D relay module 82 and correspondingbridging MAC 84, 86 for each network interconnection. The 802.1Dbridging standard defines rules to provide relay capabilities betweenthe two networks. As illustrated in FIG. 8, relay module 82 comprisesthree components: a forwarding process 88, a filtering database 90, anda learning process 92. The forwarding process 88 forwards receivedframes of data that are to be relayed to other bridge ports. Theforwarding process also filters frames on the basis of informationcontained in the filter database 90 (e.g., QoS/priority values) and onthe basis of the state of the bridge ports (e.g., on/off based on signalstrength and availability of service). The learning process 92 observesthe QoS/priority properties of frames received on each port and updatesthe filter database 90 conditionally on the port state. The filterdatabase 90 holds filtering information and supports queries by theforwarding process 88 as to whether frames with given values of thedestination MAC address are to be forwarded (relayed) to a given port.

WISE 20 then uses the priority field as defined in IEEE 802.1p to selectthe proper wireless interface. WISE 20 assigns priorities (0˜7) based onframe quality; that is, based on the frame error rate (FER). The FER canbe obtained from the wireless interface itself in most cases or can becomputed from the receive frame CRC error. The priorities assignment canalso use signal strength obtained from the wireless interface inaddition to FER and CRC. Based on this information, the networkinterface with higher priority or higher quality and higher bandwidth isselected as the preferred wireless connection.

FIG. 9 illustrates the packet header 100 used by WISE 20, which is anEthernet OSI Layer 2 packet header with an 802.1p tag controlinformation field 102. The priority value maps to the 3-bits field 104of the packet header and the tag control information field 104 maps tothe switching/packet management table 56 (see FIG. 5) as one of theswitching criteria for the filter database 90.

To enable WISE 20 to select among a plurality of wireless interfaces,channel identifications are assigned to each of the wireless interfacesbased on the IEEE 802.1Q standard. The VLAN identifier 106 is shown aspart of the tag control information field 104 in FIG. 9 is defined inthe IEEE 802.1Q standard. WISE 20 uses this field to assign networkidentification or channel numbers for LAN (interface with the mobilehost device), for WLAN, for CDMA/WCDMA or for GSM/GPRS networks so thatWISE 20 can forward data packets to the appropriate channel andcorresponding network interface.

Referring now to FIG. 10 through FIG. 13, WISE 20 can be configured tosupport various combinations of wireless interfaces as shown. FIG. 10shows a dual mode 802.11a/b configuration, FIG. 11 shows a WLAN and WANconfiguration, FIG. 12 shows a dual WLAN and WAN configuration, and FIG.13 shows a WLAN and dual WAN configuration. For example, in FIG. 10,WISE 20 has one internal interface 200 (a LAN host interface) and twoexternal wireless interfaces 202, 204, one of which is an 802.11a WLANinterface and the other of which is an 802.11b WLAN interface. A similarconfiguration is shown in FIG. 11, except that a cellular WAN interface206 is provided instead of the 801.11a interface 202 shown in FIG. 10.The configuration of FIG. 12 combines the capabilities of theconfigurations of FIG. 10 and FIG. 11 by employing all three types ofwireless interfaces; namely, 802.11a, 802.11b and WAN interfaces.Lastly, the configuration of FIG. 13 employs an 802.11b interface and aGPRS interface 208 and a CDMA interface 210. From the network IP addressconnection (OSI Layer 3) point of view, there are three IP addresses forthe mobile device in the configurations shown in FIG. 10 and FIG. 11 andfour IP addresses for the mobile device in the configurations shown inFIG. 12 and FIG. 13. In other words, there is one IP address for the LANinterface and a separate IP address for each of the wireless interfaces.

For example, assume the configuration shown in FIG. 11 which correspondsto the protocol stack shown in FIG. 2. The two external interfacesprovide gateway routing functions for the internal LAN IP address ofmobile device 18. Referring to FIG. 14, if the WLAN interface 26 is theactive interface, data packets from mobile device 18 would becommunicated from LAN interface 22 (IP0) to WLAN 14 through WLANinterface 26 (IP1). On the other hand, if the WAN interface 28 is theactive interface, data packets from mobile device 18 would becommunicated from LAN interface 22 (IP0) to WAN 12 through WAN interface28 (IP2). It will be appreciated, therefore, that the WISE 20 protocolstacks shown in FIG. 2 and elsewhere are not limiting; the protocolstack would be expanded to accommodate any particular number and/or typeof wireless interface to which mobile device 18 would be connected.

It will be appreciated, therefore, that WISE 20 provides a seamlessroaming capability to a mobile device. However, in addition to seamlessroaming, since battery life is an important consideration with anymobile device WISE can provide power management to shut down, or toplace into standby, wireless interfaces that are not being used. Forexample, referring again to FIG. 14, if WLAN interface 26 is not theactive interface, it can be powered down. Note also that, when mobiledevice 18 is moving farther way from, for example, WLAN 14, the signalquality for the WLAN interface 26 may degrade. In that instance, WISE 20can turn on WAN interface 28 in preparation for roaming when the WLANsignal is no longer usable.

While the invention has been described in terms of specific types ofwireless networks and wireless network interfaces, those skilled in theart will appreciate the invention is not so limited and that anywireless network and associated network interface can be accommodated.It will further be appreciated that the invention can be implemented infirmware and/or software using conventional hardware design andprogramming techniques. Although the description above contains manydetails, these should not be construed as limiting the scope of theinvention but as merely providing illustrations of some of the presentlypreferred embodiments of this invention. Therefore, it will beappreciated that the scope of the present invention fully encompassesother embodiments which may become obvious to those skilled in the art,and that the scope of the present invention is accordingly to be limitedby nothing other than the appended claims, in which reference to anelement in the singular is not intended to mean “one and only one”unless explicitly so stated, but rather “one or more.” All structuraland functional equivalents to the elements of the above-describedpreferred embodiment that are known to those of ordinary skill in theart are expressly incorporated herein by reference and are intended tobe encompassed by the present claims. Moreover, it is not necessary fora device or method to address each and every problem sought to be solvedby the present invention, for it to be encompassed by the presentclaims. Furthermore, no element, component, or method step in thepresent disclosure is intended to be dedicated to the public regardlessof whether the element, component, or method step is explicitly recitedin the claims. No claim element herein is to be construed under theprovisions of 35 U.S.C. 112, sixth paragraph, unless the element isexpressly recited using the phrase “means for.”

1-72. (canceled)
 73. An apparatus for switching between networkinterfaces, comprising: a switch engine configured for operating at thedata link layer of a protocol stack for a given interconnection modelconfigured for operation with multiple network interfaces; said switchengine configured to automatically select and establish a networkconnection session for a mobile device through an active interface,within the multiple network interfaces; and a bridge formed by saidswitch engine between at least two associated wireless networkinterfaces of different types in response to the mobile device roamingamong different wireless networks having different network interfaces,without closing and restarting the network connection session which hasbeen established.
 74. An apparatus as recited in claim 73: wherein saidprotocol stack comprises the Open Systems Interconnection (OSI)reference model for a TCP/IP protocol; and wherein said switch engine isconfigured for operating within the data link layer of the of saidprotocol stack.
 75. An apparatus as recited in claim 73, wherein saidswitch engine communicates with said wireless interfaces through apriority field within a packet header using tag control information. 76.An apparatus as recited in claim 75, wherein the priority field is usedto select a wireless interface based on a priority criteria selectedfrom the group of fields consisting essentially of frame quality,receive frame CRC error, and signal strength.
 77. An apparatus asrecited in claim 73, wherein said switch engine performs quality ofservice priority queuing in determining selection of the networkinterface within the multiple network interfaces.
 78. An apparatus asrecited in claim 77, wherein said quality of service priority queuing isperformed based priority, bandwidth, signal strength, frame quality,frame error rate (FER), receive frame CRC error, or combinationsthereof.
 79. An apparatus as recited in claim 73, wherein said switchengine utilizes bandwidth tagging with a tag control information fieldto control which network interface is selected.
 80. An apparatus asrecited in claim 79, wherein said tag control information field maps toa switching/packet management table as a switching criteria.
 81. Anapparatus as recited in claim 73, further comprising power managementwithin said switch engine which shuts down, or places into standby mode,network interfaces, within the multiple interface devices, which itdetermines are not the active interface device to reduce powerconsumption.
 82. An apparatus for multiple-network communications,comprising: a mobile device configured for establishing a networkconnection session for communicating with different types of wirelessnetworks through multiple network interfaces; and a switch engine,configured for operation within a data link layer of a protocol stack ofsaid mobile device, for automatically selecting one of said multiplenetwork interfaces in response to said mobile device roaming between thedifferent types of wireless networks, and without closing and restartingthe network connection session.
 83. An apparatus as recited in claim 82,wherein said switch engine operates within a data link layer of aprotocol stack.
 84. An apparatus as recited in claim 83, wherein saidprotocol stack comprises the Open Systems Interconnection (OSI)reference model for a TCP/IP protocol.
 85. An apparatus as recited inclaim 82, wherein said switch engine is configured to reduce powerconsumption in response to shutting down, or to placing into standbymode, wireless network interfaces which are not being utilized.
 86. Anapparatus as recited in claim 82, wherein said switch engine isconfigured for quality of service priority queuing when determiningselection of a network interface, within the multiple networkinterfaces, as the active network interface.
 87. An apparatus as recitedin claim 86, wherein said quality of service priority queuing isperformed based priority, bandwidth, signal strength, frame quality,frame error rate (FER), receive frame CRC error, or combinationsthereof.
 88. An apparatus as recited in claim 82, wherein said switchengine utilizes bandwidth tagging with a tag control information fieldto control which network interface is selected.
 89. A method of mobiledevice communication when roaming across multiple networks withoutclosing and restarting network connection sessions, comprising:selecting a network interface for a network connection session, frommultiple network interfaces available to a mobile device, when roamingacross multiple networks, in response to determining frame quality andusing tag control information to identify the network interface; andbridging between the mobile device and associated network interfaceswithin the protocol stack of the mobile device, and automaticallyswitching between the network interfaces as the mobile device roamsbetween multiple networks; wherein said bridging is performed betweendifferent types of wireless networks without closing and restarting thenetwork connection session.
 90. A method as recited in claim 89, whereinsaid bridging is performed within a data link layer of a protocol stack.91. A method as recited in claim 90, wherein said protocol stackcomprises the Open Systems Interconnection (OSI) reference model for aTCP/IP protocol.
 92. A method as recited in claim 89, further comprisingmanaging power consumption by identifying which network interfaces arenot active, and shutting down, or placing into standby, networkinterfaces that are not being utilized.